1. Field of the Invention:
The present invention relates to a fuel tank system, and more particularly to a fuel tank system for use on a motor vehicle such as an automobile, the fuel tank having a fuel vapor venting mechanism for smoothly guiding fuel vapors in the fuel tank toward an associated mechanism such as a canister when the fuel tank is refueled.
2. Description of the Relevant Art:
Sealed fuel tanks always have air spaces above the fuel level therein which are filled with fuel vapors. When fuel is supplied into a fuel tank, fuel vapors are fed from the fuel tank to an associated mechanism such as a canister for vapor storage.
Japanese Laid-Open Utility Model Publication No. 61-93320 discloses a fuel tank system coupled to a canister. The disclosed fuel tank system includes a fuel filler pipe connected to a fuel tank and having therein a guide for guiding a refueling nozzle and a swingable shutter. The fuel tank is connected to a canister through a fuel vapor venting pipe which has a valve therein. When the refueling nozzle is inserted into the fuel filer pipe to cause the shutter to swing, the valve in the fuel vapor venting pipe is moved an interval corresponding to the angle through which the valve swings. The fuel vapor venting pipe is now opened to allow fuel vapors to enter the canister.
Since the interval of movement of the valve varies depending on the angle of swinging movement of the shutter, when the shutter swings a smaller angle owing, for example, to the refueling nozzle failing to be fully inserted, the valve moves a correspondingly smaller interval, thus reducing the opening of the fuel vapor venting pipe. Under such a condition, the resistance presented by the fuel vapor venting pipe to the flow of fuel vapors therethrough is increased, and the fuel tank may not be smoothly refueled.